CA-122445: get_current_initiator_name fails to parse initiatorname.iscsi file on Debian

On Debian, the /etc/iscsi/initiatorname.iscsi file has comments telling you
what to do with the InitiatorName parameter;  the previous code would try
to interpret this comment as the InitiatorName setting and fail to parse it.

Signed-off-by: Euan Harris <euan.harris@citrix.com>
Reviewed-by: Thanos Makatos <thanos.makatos@citrix.com
Imported-by: Siddharth Vinothkumar <siddharth.vinothkumar@citrix.com>

(cherry picked from commit 6c45c1717a2c842b1e7e3878628032e0412dd467)